Gas compressing apparatus and method of regulating the same



Aug. 26, 1941. H. PFENNINGER' 2,253,809

GAS COMPRESSING APPARATUS AND METHOD OF REGULAT ING THE SAME Filed Dec. 15, 1959 Qddhf Yy I 7 v 14/1 Compressor Ouijoaf Patented Aug. 26, 1941 'GAS COMPRESSING APPARATUS AND METHOD OF REGULATING THE SAME Hans Pfenninger, Wettingen, Switzerland, as-

signor to Aktiengesellschatt Brown, Boveri Cie, Baden, Switzerland, a joint-stock company Application December 15, 1939, Serial No. 309,507 In Germany'December 27, 1938 9 Claims.

The invention relates to gas compressing apparatus and methods 01 regulating the same, and more particularly to apparatus for delivering hot gases under pressure for chemical, metallurgical' or other uses.

7 apparatus.

An object of the invention is to provide relatively simple gas compressor plants including a constant pressure gas turbine, a single combustion chamber for producing the hot combustion gases for operating the gas turbine and heating the useful output gas, and correlated control apparatus for regulating the turbine operation in accordance with the temperature, pressure or quantity of the output gas. Another object is to provide a compressor plant of the type stated for delivering hot compressed air, the plant including a single compressor for'supplying the net useful output air and the combustion air for the gas turbine that operates the compressor; Other objects are to provide novel and efiicient methods of regulating compressors directly to the turbine in accordan c with a C011,

dition of the output gas that is to be maintained substantially constant (such as temperature, pressure or quantity), whereby the speed of the gas turbine is changed and thereby affects another condition of the output gas, and

controlling the fuel supply to the combustion gas turbine to eflect a further change in the turbine speed to regain the desired conditions or characteristics of the output gas.

These and other objects and advantages of the invention will be apparent from thevfollowing specification when'taken with the a'ccompanying drawing in which:

Figs. 1 and 2 are schematic diagrams of different embodiments of the invention. Constant pressure combustion gas turbines are not-characterized by a high iefliciency but are of simple constructionand) frequently used in chemical and metallurgical plants. The gas turbine plants, as previously employed, have been self-contained power units that were controlled in various ways and the apparatus operated by the gas turbine was independently controlled, when a control was desired, in accordance with some condition or characteristic of the output The present invention contemplates a compressor plant operated by a gas turbine, with control apparatus and methods for regulating the gas turbine in accordance with variations in load on the compressor plant as reflected in a change in some conditions, such as temperature, pressure or quantity, of the useful output gas delivered by the compressor plant.

In Fig. 1, the reference numeral I identifies a combustion gas turbine that drives an air compressor 2 of such capacity as to deliver both the useful output air and the air for admixture with fuel from the pump or blower 3 for combustion to supply motives gas to the turbine and to heat the output air. The fuel may be, for example, blast furnace gas when the compressor plant is designed for use in the metallurgical industry to supply hot compressed air as the blast for a furnace. Air from compressor 2 flows through pipe 2' and absorbsv heat from theturbine exhaust gases in a heat exchanger 4, and a p-artof the heated compressed air passes to the burner 5 of a combustion chamber 6 in which is located the heat exchanger! to which the useful output air is delivered through the passage 8. Another portion of the compressed air from the heat exchanger 4 goesdirectly to 'the inlet of turbine I through the bypass pipe 9 and regulating valve III. In general, the hot gases that pass from the combustion chamber 6 to the turbine I through pipe 9' are at such high temperature that some admixture of lower temperature air is necessary for the protection of the gas turbine.

The rate of.flow of the cooling air through valve 10 is regulated by a control device II in the discharge conduit from the heat exchanger I, and the type oi control device depends paratus is as follows. If the temperature of the output air departs from a predetermined value, for example if it is too low, the thermostat l adjusts valve ill to a more open position to permt a greater quantity of air to pass to the turblue I through the bypass pipe 9. Lessair is therefore suppliedto the burner '6 and the temperature in the combustion chamber 6 rises and the temperature of the output air is thereby increased. The quantity of output air is diminished, however, as the delivery of a larger quantity of air through the bypass pipe '9 results in a lower speed 'of the turbine l. The quantity meter I2 therefore adjusts the fuel supply valve I: to. increase the fuel feed and thereby increase the temperature of the motive gas to pressor 2., The same general method of controlturbine I. The gas turbine speed increases with the temperature of. the motive gas and the output from compressor 2 rises until air flow through the quantity meter l2 returns to the normal or preselected value. At the same time, the valve I is returned to its normal setting by ther- 'trol device l2, which may be a quantity meter or a pressure gauge, controls the fuel supply'fr'om the pump 3. I In place of the throttle valve 13 of Fig. l, the control fromdevice I! is imposed upon a variable speed motor {6 that drives the fuel pump 3. Other arrangements are possible by incorporating some of the features of the Fig. 2

, compressor p1ant in' the Fig. 1 construction or by supplying combustion air to the burner through the lower pressure output line 2a of comling the turbine operation in accordance with two properties of the useful output gas is characteristic of the Fig. 2 embodiment and a detailed statement of the method of operation is not believed to be necessary.

mostat II when the temperature of the output 3 compressed air returns to normal.

Similarly, if the output quantity of air varies without change in its temperature, the quantity-meter l2 adjusts the fuel supply valve I3 to restore the desired operating condition. .If

the air output increases to a value above a preselected load demand, the quantity meter [2 adjusts valve [3 to reduce the fuel supply and all temperatures therefore decrease. The speed of the turbine falls off and'the volume of air deli'vered by compressor 2 decreases. Thermostat ll effects a partial opening of the bypass valve temperature in the combustion chamber 6 therefore increases to effect a corresponding increase in the outlet air temperature.

It will be apparent that substantially the'same control operations may be effected by interchanging the connections between the control devices 1. In a plant for producing hotgases under pressure, the combination of a combustion gas. turbine, a gas compressor driven by said turbine, a combustion nozzle for generating the combustion gas for operating said turbine, a. heat ex: changer through which the combustion gases pass, means for delivering a part of the gas from said compressor to said nozzle and another part through said heat exchanger to anoutput pipe, a

III as the outlet temperature decreases, and the H, I! and the valves l0 and I3. The sequence of control steps will be varied by this exchange but the net result will be the same.

The fuel supply valve [3 may be a bypass valve at the outlet side of the blower 3 in place of the illustrated throttling valve. in the inlet line to the blower 3. Installations in which the pressure.

of the output air is more important than the output quantity will have a control device I2 in the form of a pressure gauge.

There'is considerable latitude in the design and construction of a gas or air compressor plant that may be regulated in accordance with this invention and certain modifications are shown in the embodiment of Fig. 2. Those parts that are or may be substantially identical withparts' shown in Fig. 1 are identified by corresponding reference numerals but will not be described in detail. The

air supplied through the bypass pipe 9 maybe pressure, the invention as claimed in claim f1,

wherein one controldevice is a thermostat the other is a quantity meter.

3. In a plant for producing pressure, the invention as claimed in claim 1,

and

wherein one control device is a thermostat and the other is a'pressure gauge.- v

4. In a. plant for producing hot gases under pressure, the invention as claimed in claim 1, wherein the means for regulating the turbine speed includes a bypass pipe for supplying gas from said compressor to the inlet of said turbine for admixture with combustion gases from said combustion-nozzle, and a valve in said bypass pipe operable by the associated control device.

taken from an intermediate stage of the'co'm-- pressor 2 through pipe 2a when there is a substantial drop of pressure in the flow of combustion gases through the heat exchanger I. The air for combustion and the useful output air leave compressor 2, as in the Fig. l "embodiment, through the high pressure pipe 2', and the heat exchanger 4' has separate sections for the air from pipe 2a and that from pipe 2'.

An auxiliary turbine 14 that exhausts into the inlet line 8' of turbine I may serve as the means for regulating the speed or energy output of the turbine unit. As shown in Fig. 2, the auxiliary an inlet supp y controlled turbine ll has a plurality of nozzles l-5 that receive a pressure medium through the bypass-pipe I and are opened in sequence in accordance with changes in a characteristic of-the output pressure air, for example by the thermostat H. The con- 5. In a plant for producing hot gases under pressure, the invention as claimed in claim 1,

wherein the means for regu1ating"the turbine speed includes a bypass pipe for supplying" gas from said compressor .to the inlet of said turbine foradmixture with combustion gases from said combustion nozzle, said compressor is a multistage air compressor, and means is provided for supplying air to said bypass pipe from an intermediate stage of said air compressor.

6. In a plant 'for producing hot gases under pressure, the invention as claimed in claim 1, wherein said means for regulating the speed of saidturbine includes an auxiliary turbine having by the first of said control means. v

7. In the operation of a compressor plant including a combustion gas turbine driving a turbine, and a combustion chamber for producing motive gas for said turbine and for heating a 7 portion ofthe compressor output do; deliveiyto hot gases under I turbine and to an output pipe after passing in heat exchange relation to the combustion gases; a bypass for supplying air to said turbine around said combustion nozzle, and means for regulating the fuel supply to said combustion nozzle; the

method of regulating said turbine to maintain predetermined properties of the air at said outlet pipe substantially constant which comprises controlling the fiow of air through said bypass in ac- 3 cordance with one property of the air flowing through said output pipe, and controlling the fuel supply to said combustion nomle in accordance with another property of the air flowing through \said output pipe.

9. In the operation of a compressor plant including a combustion gas turbine driving an air compressor, a combustion nozzle receiving air from said compressor and fuel from a fuel pump; and an outlet pipe through which air-flows from said compressor after passing in heat exchange relation to combustion gas produced by said com; bustion nozzle, the method of regulating the op.- eration of said turbine that comprises independ ently controlling two properties of the motive, gas

supplied to said turbine in accordance with changes in two characteristics of the'air flowing through said outlet pipe ms rrnnumonn. 

